diff --git a/avatar/proto/avatar.proto b/avatar/proto/avatar.proto
index eb11faf..792d967 100644
--- a/avatar/proto/avatar.proto
+++ b/avatar/proto/avatar.proto
@@ -8,6 +8,7 @@ service Avatar {
   rpc Generate(GenerateRequest) returns (GenerateResponse) {}
 }
 
+// Generate an unique avatar
 message GenerateRequest {
   // avatar's gender, `male` or `female`, default is `male`
   string gender = 1;